Tire balancing machine system

ABSTRACT

A system for reducing undue vibrations transmitted to a vehicle by a tire assembly including a tire buffing or grinding machine, a tire balancing machine, and a mounting adapter for alternatively mounting the tire assembly on the tire buffing machine and the tire balancing machine. The tire buffing machine includes a drive unit for rotating the tire assembly about its rotational axis, a loading unit for radially loading the tire assembly, a buffing unit for selectively grinding away portions of the tire tread, and a control unit interconnecting the loading unit and the buffing unit to cause the buffing unit to reduce the loaded radial runout of the tire assembly.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of my co-pending application Ser. No.709,544, filed July 28, 1976, now U.S. Pat. No. 4,139,041.

BACKGROUND OF THE INVENTION

Because vehicular tires support the sprung mass of a vehicle on a roadsurface and such tires are resilient, any irregularities in thedimensions of the tire or in its resiliency, any dimensionalirregularities in the wheel rim, and/or any dynamic imbalance of thewheel rim and tire assembly will cause undue vibrations to betransmitted to the sprung mass of the vehicle thereby producingundesirable ride characteristics commonly known as "smooth road shake".One technique almost always used to reduce smooth road shake is tobalance the wheel rim and tire assembly. For a number of years, theindustry attempted to further reduce smooth road shake by measuring theunloaded radial and lateral runout of tires mounted on a wheel rim andremoved portions of the tire tread to reduce the unloaded radial andlateral runout with a tire truing machine. Such machines are emplifiedin U.S. Pat. Nos. 3,752,207; 2,966,011; and 2,918,116. Because smoothroad shake is generated when the tire is loaded by vehicular weight, thetire truing machines have not been successful in eliminating smooth roadshake even when balancing was used. More recently, the automotiveindustry has begun using a technique known as "force variation tiregrinding" in addition to balancing in an attempt to reduce the unduevibrations transmitted in the sprung mass of the vehicle. A number ofdevices using this technique have been proposed such as those shown byU.S. pat. Nos. 3,553,903; 3,681,877; and 3,725,137. While such deviceshave been relatively successful in reducing the undue vibrationstransmitted to the sprung mass of the vehicle by the tires, theircomplexity, manufacturing cost, and the requirement of trained operatingpersonnel has limited the use of these device primarily to themanufacturing facilities of the vehicle tire manufacturing companies.This has resulted in improved ride characteristics with respect to theoriginal equipment tires on the vehicle but has done little to maintainthe original improved ride characteristics when these original equipmenttires are replaced by the second market. Further, these prior artdevices have usually mounted the tire on an axle or arbor for testingrather than on the vehicular wheel rim. Because the wheel rim itself canhave dimensional inaccuracies which affect the undue vibrationstransmitted to the sprung mass of the vehicle, correcting the tires withforce variation tire grinding without the tire being mounted on thewheel rim on which it is to be used with the vehicle frequently failedto compensate for the total irregularities of the wheel rim and tirecombination even in combination with balancing.

In an attempt to compensate for the undue vibrations transmitted to thesprung mass of the vehicle by the wheel rim and tire combination inaddition to balancing, a machine has been suggested that reduces theloaded radial runout of the wheel rim and tire combination while thewheel rim and tire combination is mounted on the vehicle. Such a deviceis disclosed in R. J. Caulfield and R. J. Higgins: "On-Car Tire Grinderfor Improved Ride Smoothness" presented at the National AutomobileEngineering Meeting, Detroit, Mich. (May, 1972) SAE Paper No. 720465. Asimilar device is shown in U.S. Pat. No. 3,905,160. Because theseon-the-car grinders use the weight of the vehicle to load the wheel rimand tire combination, a great deal of effort must be expended to insurethat the vehicle is substantially level and to insure that the sprungmass of the vehicle is properly supported by the wheel rim and tirecombination in order to obtain proper loading during testing andgrinding. Because the loading drum is also used to rotate the wheel rimand tire combination and the spacial relationship of the grinding raspswhich grind the tire is controlled from the support frame carrying thedrum, any slippage between the loading drum and tire results in thewheel rim and tire combination being improperly corrected. Further,because the rotational axis of the loading drum and the pivot axis ofthe grinding rasps support arm are held stationary in the grinder framewhile the rotational axis of the wheel rim and tire combination can movewith respect to both the drum rotational axis and the grinding arm pivotaxis, the angular spacing between the loading point on the tire and thegrinding point on the tire varies as the wheel rim and tire combinationmoves with respect to the loading drum rotational axis. This also causesimproperly corrected tires.

SUMMARY OF THE INVENTION

These and other problems associated with the prior art are overcome bythe invention disclosed herein by providing a tire correction systemusing an off-the-car tire buffer which is capable of correcting theloaded radial runout of an inflated tire mounted on a wheel rim and anoff-the-car dynamic balancer to also balance the wheel rim and tireassembly to eliminate smooth road shake. The buffer is simple inmanufacture, easy to operate, and accurate in operation. The buffer isarranged to compensate for deflection of the components of the machinedue to the radial loading of the tire thereby allowing lightweight framecomponents to be used. The buffing head is accurately positionedadjacent the tire tread using a first force urging the buffing headtoward engagement with the tire tread and a second force generatedthrough a tread engaging assembly to oppose the first force to cause thebuffing head to float in a neutral position adjacent the tire treaduntil a third force greater than the second force urges the buffing headinto contact with the tire tread. The support arm assemblies movablymounting the tire loading drum and the buffing head are sized andlocated to allow different size tires to be accurately ground withoutmachine adjustment. A mounting adapter is provided which accuratelymounts the wheel rim and tire assembly so that the effective rotationalaxis of the assembly is aligned with the adapter central axis. Themounting adapter is removably and interchangably mountable on either thebuffer or balancer and is keyed to each for positive driving of thewheel rim and tire assembly.

The apparatus of the invention includes a tire buffer, a tire balancerand a mounting adapter for supporting an inflated pneumatic tire whilemounted on a vehicular wheel rim on either the tire buffer or tirebalancer. The tire buffer includes generally a base frame which carriesa tire driving assembly with a buffer drive spindle to mount andpositively rotate an inflated pneumatic tire mounted on a vehicularwheel rim and supported on the mounting adapter; a loading drum assemblycarried by the base frame and pivotable into engagement with the tiretread to radially load the tire; and a buffer assembly carried by thebase frame and pivotable into engagement with the tire tread toselectively buff or grind away portions of the tire tread. The loadingdrum assembly includes a loading arm assembly pivoted to the base framefor movement toward and away from the tire tread by a loading cylinder,a drum yoke assembly pivoted on the loading arm assembly, and a loadingdrum rotatably mounted on the drum yoke assembly that engages the tiretread to radially load the tire. The pivotal position of the yokeassembly relative to the loading arm assembly is resiliently controlledso that the yoke is moved in response to variations in the loaded radialrunout of the tire assembly. The buffer assembly includes a buffer armassembly pivoted to the base frame for movement toward and away from thetire tread, a buffer head assembly mounted on the buffer arm assemblythat engages the tire tread at a point angularly translated from theloading drum to selectively buff or grind away portions of the tiretread, a buffer arm positioning assembly that moves the buffer armassembly relative to the tire tread and loading arm assembly and whichis interconnected to the loading arm assembly to move the buffer armassembly inwardly toward the tire tread as the loading arm assembly ismoved inwardly toward the tire tread, and a spacer assembly forselectively urging the buffer head away from the tire tread inopposition to the buffer arm positioning assembly to locate the bufferhead in a neutral position closely adjacent the tire tread. The bufferarm positioning assembly resiliently urges the buffer arm assemblytoward the tire tread with a first positioning force offset by thespacer assembly and also forces the buffer arm assembly toward the tiretread with a second buffing force greater than the opposing force of thespacer assembly to cause the buffer head assembly to engage the tiretread. The driving spindle of the tire driving assembly is positivelyrotated and is removably keyed to the tire mounting adapter, topositively drive both the mounting adapter and wheel rim and tireassembly mounted on the mounting adapter. The drive spindle iscantilevered and angled toward the loading drum so that the deflectionof the drive spindle under the loading of the tire assembly aligns theaxis of the drive spindle with the axis of the loading drum.

The tire balancer of the invention includes generally a balancer drivespindle thereon to mount and positively spin the wheel rim and tireassembly supported on the mounting adapter. The balancer drive spindleis also removably keyed to the mounting adapter so that the mountingadapter can be shifted from the buffer to the balancer without removingthe wheel rim and tire assembly therefrom.

The mounting adapter is removably and alternatively mountable on thebuffer drive spindle and the balancer drive spindle so that the adaptercentral axis is coaxial with the rotational axis of the spindle mountingthe adapter. Further, a keyed connection is provided between the adapterand each drive spindle so that the adapter will be positively driven bythe drive spindle on which it is mounted. The adapter selectively mountsthe wheel rim and tire assembly thereon so that the normal effectiverotational axis of the wheel rim and tire assembly coincides with themounting adapter central axis and is keyed to the adapter for positiverotation therewith.

These and other features and advantages of the invention will becomemore apparent upon consideration of the following specification andaccompanying drawings wherein like characters of reference designatecorresponding parts throughout the several views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a machine embodying the inventionwith a wheel rim and tire mounted thereon;

FIG. 2 is an enlarged rear elevational view of the machine of FIG. 1with the covers removed;

FIG. 3 is an enlarged cross-sectional view taken along line 3--3 in FIG.2;

FIG. 4 is a reduced longitudinal cross-sectional view taken along line4--4 in FIG. 3;

FIG. 5 is an enlarged top view of the buffer assembly taken along line5--5 in FIG. 4;

FIG. 6 is a cross-sectional view of the buffer assembly taken along line6--6 in FIG. 5;

FIG. 7 is a view similar to FIG. 6 showing an alternate buffer spacerassembly;

FIG. 8 is an enlarged transverse cross-sectional view taken along line8--8 in FIG. 7;

FIG. 9 is a longitudinal cross-sectional view taken along line 9--9 inFIG. 8;

FIG. 10 is an enlarged view similar to FIG. 4 showing a mounted tireassembly in operative position on the machine;

FIG. 11 is a left elevational view of FIG. 10;

FIG. 12 is an enlarged exploded view of an adapter assembly to mount thetire assembly on the machine;

FIG. 13 is a view similar to FIG. 12 with the adapter assemblyassembled;

FIG. 14 is a front view of the adapter assembly of FIG. 13;

FIG. 15 is an enlarged exploded view similar to FIG. 12 with a differentwheel mounting assembly;

FIG. 16 is a face view taken along line 16--16 in FIG. 15 with the wheelmounting assembly assembled; and,

FIG. 17 is a schematic diagram of the control circuit;

FIG. 18 is a front view of a balancer machine of the invention;

FIG. 19 is an enlarged view shown partly in cross-section of the adapterof FIG. 13 mounted on the balancer drive spindle;

FIG. 20 is a view of the support sleeve of the adapter mounted on thebalancer drive spindle with portions thereof broken away to show themounting: and,

FIG. 21 is an enlarged view of the balancer drive spindle.

These figures and the following detailed description disclose specificembodiments of the invention, however, the inventive concept is notlimited thereto since it may be embodied in other forms.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The invention is designed to test and correct smooth road shake problemsassociated with a tire assembly, that is, an inflated pneumaticvehicular tire mounted on a vehicular wheel rim. The pneumatic tire T(FIG. 1) has a peripheral road engaging tread TT thereon while the wheelrim WR has a central disk CD that defines lug holes LH (FIG. 13) thereinand a central axle opening CO (FIG. 13) therethrough so that the wheellugs on a vehicle can mount the tire assembly TA on the vehicle.

The tire correction system of the invention includes a buffing machine10 seen in FIGS. 1-11; a balancing machine 300 seen in FIG. 18; and amounting adapter 54 seen in FIGS. 12-16, 19 and 20. The mounting adapter54 mounts the tire assembly TA thereon so that the effective rotationalaxis of the tire assembly TA coincides with the adapter central axis.The adapter 54 can then be used to alternatively mount the tire assemblyTA first on the buffing machine 10 to test and correct the tire assemblyfor excessive loaded radial runout and secondly on the balancing machine300 to balance the tire assembly.

As seen in FIG. 1, the buffing machine 10 of the invention includesgenerally a base frame 11 which mounts a tire driving unit 12 thereon tosupport and rotate the adapter 54 with the tire assembly TA; a tireloading unit 14 which radially loads the tire T; and a buffer unit 15which selectively buffs or grinds away portions of the tire tread TT inresponse variations in loaded radial runout of the tire T against theloading unit 14. Provision is made for automatically testing the tireassembly TA to determine if the variations in the loaded radial runoutexceed a prescribed limit and to buff the tire tread TT until thevariations in the loaded radial runout fall below the prescribed limit.It will be noted that the tire assembly TA is removed from the vehiclewhile it is being tested and corrected thereby making the machine 10 an"off-the-car" machine.

For purposes of this application, loaded radial runout shall mean thevariations in radial dimension of the tire tread TT from the tireassembly rotational axis while the tire assembly TA is under aprescribed load through its peripheral tread TT at a loading position atwhich the radial dimension is measured. Because all of the tread TT isrotated through the loaded position, the loaded radial runout ismeasured along the entire length of the peripheral tread TT.

BASE FRAME

Referring to FIGS. 2-4, the base frame 11 includes an open rectilinearbase 20 which sits on the floor to support the machine. Base 20 has abase centerline CL-B (FIG. 3) and includes spaced apart, parallel sidechannels 21 joined at opposite ends by spaced apart, parallel endchannels 22. The side channels 21 are joined intermediate their ends byan intermediate cross plate 24 (FIGS. 3 and 4) normal to centerlineCL-B. A pair of opposed, parallel, spaced apart cylinder supportchannels 25 extend between the cross plate 24 and the left end channel22 as seen in FIGS. 3 and 4 which are oriented parallel to thecenterline CL-B and centered on the tread central plane P_(VT) of thetire assembly TA as seen in FIG. 11. A pair of opposed, parallel, spacedapart motor support angles 26 extend between the cross plate 24 and theright end channel 22 as seen in FIGS. 3 and 4 which are also orientedparallel to the centerline CL-B. A pair of opposed, upstanding loadingarm pivot plates 28 are mounted on the right end channel 22 as seen inFIGS. 3 and 4 with their upper ends joined by a tie plate 29. A pair ofshorter opposed, upstanding buffer pivot plates 30 are mounted on sidechannels 21 between the cross plate 24 and right end channel 22 as seenin FIGS. 3 and 4. An upstanding support post 31 is mounted on the base20 at the far corner between the rear side channel 21 and the left endchannel 22 as seen in FIG. 3. The tire driving unit 12 is mounted on topof post 31; the tire loading unit 14 is pivoted between the upper endsof the loading arm pivot plates 28 about pivot axis A_(DA) normal tobase centerline CL-B; and the buffer unit 15 is pivoted between theupper ends of the buffer pivot plates 30 about pivot axis A_(BA) alsonormal to base centerline CL-B.

TIRE DRIVING UNIT

Referring to FIGS. 2, 4 and 11, the tire driving unit 12 mounts the tireassembly TA so that the tire T can be loaded by the loading unit 14 andbuffed by the buffing unit 15. The driving unit 12 includes a spindleplatform 35 mounted on the top of post 31 so that its upper surface isgenerally parallel to and spaced above the axis A_(DA) and A_(BA).Appropriate braces 36 reinforce platform 35. An inverted U-shaped motorbracket 38 is mounted on opposite sides of platform 35 and extendsthereabove.

A drive spindle assembly 39 (FIGS. 4 and 11) is carried on the uppersurface of platform 35. The spindle assembly 39 includes an elongatedrive spindle 40 which is rotatably journalled in bearing blocks 41mounted on platform 35 so that the front projecting end 42 of spindle 40extends forwardly in cantilever fashion over the loading unit 14. Therotational axis A_(DS) of spindle 40 is generally parallel to the pivotaxes A_(DA) and A_(BA). The rear projecting end 44 (FIG. 11) of spindle40 extends rearwardly from the platform 35 to mount a driven sprocket 45thereon.

A drive unit 46 (FIG. 11) is carried by the bracket 38 above the spindleassembly 39. The drive unit 46 includes a gear reducer 48 coupled to adrive motor 49 so that the output shaft 50 of the gear reducer 48extends rearwardly of bracket 38 and mounts driven sprocket 51 thereon.A drive chain 52 connects sprockets 45 and 51 so that motor 49positively rotates the drive spindle 40. While the motor 49 may rotatethe spindle 40 at any selected speed, a spindle rotation speed of about20 rpm has worked satisfactorily. It will further be noted that thespindle 40 has a projecting length L_(DS) (FIG. 11) such that it extendsacross and over the loading unit 14 as will become more apparent.

The tire assembly TA is mounted on spindle 40 through mounting adapter54 (FIG. 11) described more fully hereinafter. The adapter 54 mounts thetire assembly TA on the spindle 40 so that the spindle axis A_(DS)coincides with the effective rotational axis of the tire assembly TAwhen mounted on a vehicle. Thus, as the tire assembly TA rotates withthe spindle 40, the tire assembly TA is rotated about its effectiverotational axis on the vehicle. The position of the tire assembly TAlongitudinally of the spindle 40 is controlled by a stop 55 which can beselectively fixed to spindle 40 by a set screw 56 seen in FIG. 13. Thestop 55 limits the forward movement of the tire assembly TA along thespindle 40 and is located behind the tire assembly TA. Because thespindle 40 is cantilever mounted from the platform 35, there is atendency for the spindle 40 to be deflected away from the loadingposition of the tire T unless the frame 11 and spindle 40 are madeextremely strong. This problem is solved by angling the projecting end42 of spindle 40 toward the loading position P_(L) on the tire T in thediametrically extending loading plane P_(VL) passing through loadingposition P_(L) in FIG. 10. The amount of the angle A-SP as seen in FIG.11 when the tire T is unloaded is selected so that the axis A_(DS) ofspindle 40 will be shifted up to a position so that the axis A_(DS) issubstantially parallel to the axes A_(DA) and A_(BA) when the tire T isloaded. The loaded position is shown in FIG. 11 with the axis A_(DS)shown in its unloaded position by a phantom line in FIG. 11. This alsoserves to constantly urge the tire assembly TA rearwardly along thespindle 40 when it is loaded so that it is not necessary to lock thefront side of the tire assembly TA onto the spindle.

To insure that the tire assembly TA will be positively driven by thespindle 40, a drive key 58 (FIG. 11) is provided along spindle 40 toengage the adapter 54 as will be explained. Thus, a positive timingrelationship is maintained between the loading position and the buffingposition. The drive key 58 has a constant width W_(DK) along its lengthand a constant exposed as seen in FIG. 14 along its length as willbecome more apparent.

TIRE LOADING UNIT

The tire loading unit 14 best seen in FIGS, 3, 4 and 10 serves toradially load the tire T through its peripheral tread TT to determinethe radial runout of the loaded tire assembly TA. The loading unit 14includes a loading arm assembly 60 which is pivoted at one end to thedrum pivot plates 28 about the axis A_(DA), a drum yoke assembly 61pivoted to the loading arm assembly 60 about a yoke pivot axis A_(DY)parallel to axis A_(DA), and a loading drum 62 rotatably mounted on theyoke assembly 61 about rotation axis A_(D) generally parallel to axesA_(DA) and A_(DY). Thus, it will be seen that the pivot axis A_(DY) ispivoted about axis A_(DA) as the arm assembly 60 is pivoted. The drumrotational axis A_(D), on the other hand, is pivoted about the pivotaxis A_(DY) as the yoke assembly 61 is pivoted with respect to theloading arm assembly 60 and also may be pivoted about the arm axisA_(DA) along with yoke assembly 61 as the arm assembly 60 is pivoted.

The loading arm assembly 60 is stepped with primary frame section 65which mounts the yoke assembly 61 and a secondary frame section 66 whichconnects the primary frame section 65 to the pivot plates 28. Theprimary frame section 65 includes a pair of opposed, parallel sidechannels 68 which are parallel to the base centerline CL-B. The leftends of the side channels 68 seen in FIGS. 3 and 4 are joined by atransverse front L-shaped plate 69. The vertical leg 70 of front plate69 is higher than side channels 68 so that the horizontal leg 71 thereofis located below and extends rearwardly under side channels 68 as willbecome more apparent. The right ends of the side channels 68 seen inFIGS. 3 and 4 are joined by a back channel 72 flush with the upper edgesof the side channels 68. Thus, the primary frame section 65 defines ayoke receiving opening 74 bounded by side channels 68, front plate 69,and back channel 72.

The secondary frame section 66 includes a pair of side angles 75connected to the back channel 72 of primary frame section 65 andprojecting to the right in FIGS. 3 and 4. The right ends of side angles75 in FIGS. 3 and 4 are joined by an end plate 76. A pivot tube 78 isconnected to the right side of end plate 76. A pivot shaft 79 isrotatably received through tube 78 and is journalled between the upperends of pivot plates 28. Thus, the arm assembly 60 is pivoted about thecenterline of shaft 79 which is the axis A_(DA).

The yoke assembly 61 is pivotally mounted between the side channels 68in the primary frame section 65 of loading arm assembly 60. The yokeassembly 61 includes a pair of opposed, parallel side angles 80generally parallel to base centerline CL-B (FIG. 3) joined at their leftends by front angle 81 and just inwardly of their right ends by backangle 82. The right ends of side angles 80 are pivoted on pivot shaft 84which is journalled between the side channels 68 of primary framesection 65. The centerline of shaft 84 forms yoke axis A_(DY). The sizeof yoke assembly 61 and location of yoke axis A_(DY) are such that theyoke assembly 61 pivots in the yoke receiving opening 74 withoutinterfering with the loading arm assembly 65.

A pair of drum bearing blocks 85 are mounted opposite each other on theside angles 80 of yoke assembly 61. The bearing blocks 85 rotatablyjournal the loading drum 62 therebetween about drum axis A_(D).

The loading drum 62 includes a cylindrical side wall 86 mounted on adrum axle 88 by end pieces 89 so that side wall 86 is concentric aboutaxle 88. Axle 88 is rotatably journalled between bearing blocks 85 sothat the centerline of axle 88 if the rotation axis A_(D).

The pivotal position of yoke assembly 61 and thus drum axis A_(D) aboutaxis A_(DY) relative to the primary frame section of loading armassembly 60 is controlled by a spring assembly 90 which resilientlyconnects the front angle 81 on yoke assembly 61 to the horizontal leg 71on front plate 69 of loading arm assembly 60 as seen in FIGS. 4 and 10.The spring assembly 90 includes a plurality of compression coil springs91 positioned between angle 81 on yoke assembly 61 and leg 71 on loadingarm assembly 60. The springs 91 are held in position by keepers 92 andbolts 94. The bolts 94 limit the extension of springs 91 and may beeasily removed to change the springs 91 for different loading values orfor replacement. The number of springs 91 may be varied, however, fourare shown (FIG. 3). Thus, when the loading arm assembly 60 is pivotedclockwise upwardly about axis A_(DA) from its unloaded position seen inFIG. 4 toward its loaded position seen in FIG. 10, the tire tread TTengages the side wall 86 of loading drum 62 and forces the yoke assembly61 counterclockwise about axis A_(DY) from the unloaded position seen inFIG. 4 toward its loaded position seen in FIG. 10 against springs 91.

A motion or displacement transducer 95 is mounted centrally of frontplate 69 as seen in FIGS. 10 and 11 so that its operating plunger 96will be engaged by a drive pin 98 carried by an offset bracket 99 onyoke assembly 61. When drive pin 98 engages plunger 96 on transducer 95,the movement of yoke assembly 61 produces a corresponding change inoutput from transducer 95. This output is indicative of the loadedradial runout of the tire assembly T.

The loading arm assembly 60 is positioned by a loading cylinder 100which is pinned to the base 20 by a pin 101 (FIG. 10) extending betweenthe support channels 25 and oriented normal to the base centerline CL-B.The piston rod 102 from cylinder 100 is pinned to the center of theunderside of the back channel 72. Thus, as piston rod 102 is extended,the loading arm assembly 60 is pivoted clockwise to cause the loadingdrum 62 to engage the tire tread TT as seen in FIG. 10. As piston rod102 is retracted, the loading arm assembly 60 is pivotedcounterclockwise to release the tire tread. When the tire assembly TA isproperly loaded, the loading cylinder 100 is locked to maintain the loadon the tire assembly.

BUFFER UNIT

The buffer unit 15 as best seen in FIGS. 2-6 serves to selectively buffor grind the peripheral tread TT of the tire T to reduce the loadedradial runout indicated by transducer 95 to an acceptable level. Thebuffer unit 15 includes a buffer arm assembly 110 (FIGS. 3 and 4) whichis pivoted at one end between the buffer pivot plates 30 about thebuffer pivot axis A_(BA), a buffer head assembly 111 (FIGS. 4-6) mountedon the upper end of the buffer arm assembly 100, a buffer spacerassembly 112 (FIGS. 4-6) carried by the upper end of the buffer armassembly 110 adjacent the buffer head assembly to position the bufferhead assembly 111 with respect to the tire tread TT, and a buffer armpositioning assembly 114 (FIGS. 3 and 4) which positions the buffer armassembly 110 to selectively locate the buffer head assembly 111 adjacentthe tire tread.

The buffer arm assembly 110 includes a pair of opposed upstanding sidechannels 115 with the side channels 115 being positioned just outboardof the side angles 75 of the secondary frame section 66 on the loadingarm assembly 60. The side channels 115 are parallel to each other andgenerally normal to the pivot axis A_(BA) of the buffer unit 15. Theside channels 115 are connected along their right edges as seen in FIGS.4 and 6 by an offset back plate 116 to maintain the side channels 115 ata spaced apart position. A tie bar 118 connects the side channels 115just below the secondary frame section 66 of the loading arm assembly 60as best seen in FIG. 4. The tie bar 118 is located sufficiently farbelow the secondary frame section 66 so that the tie bar 118 will clearthe secondary frame section 66 as the buffer unit 15 and the loadingunit 14 are pivoted with respect to each other. A Z-shaped deflectorplate 119 extends between the side channels 115 above the secondaryframe section 66 as seen in FIG. 4. The deflector plate 119 serves toreinforce the buffer arm assembly 110 while at the same time deflectingany grindings or dust generated by the buffer head assembly 111 outboardof the working components of the machine. The lower end of the frontside channel 115 is connected directly to the front buffer pivot plate30 while the rear side channel 115 is connected to the rear buffer pivotplate 30 through a U-shaped pivot bracket 120 as best seen in FIGS. 2and 3. The buffer arm assembly 110 is pivoted to the pivot plates 30 bystub shafts 121 carried by the front side channel 115 and the pivotbracket 120.

The buffer head assembly 111 includes a driven shaft 125 which isjournalled between bearing blocks 126 mounted at the upper end of theside channels 115 as seen in FIG. 5, so that the rotational axis A_(BH)of the driven shaft 125 is parallel to the buffer arm pivot axis A_(BA)and spaced thereabove. A pair of buffing rasps 128 are mounted on thedriven shaft 125 as best seen in FIGS. 5 and 6 and are locked onto theshaft 125 by lock screws 129 seen in FIG. 6 so that the buffing rasps128 can be slidably positioned longitudinally of the shaft 125 andlocked onto the shaft 125 by the lock screws 129. Each of the buffingrasps 128 defines a tapered exterior roughened buffing surface 130thereon which tapers inwardly toward the center of the tire at an angleA-B best seen in FIG. 5. While different angles A-B may be used, anangle of about 5° has been found appropriate. It will also be noted thatthe buffing surface 130 of each rasp 128 has a width W-B which isusually about three inches and that the outboard edges of the buffingrasps 128 are located outboard of the tire central plane P_(VT) of thetire assembly TA as seen in FIG. 5 a distance D-B. Thus, it will be seenthat the rasps 128 are centered on the tire central plane P_(VT) and thedistance D-B is selected so that the outboard edges of the rasps 128 arelocated just outboard of the outboard shoulders of the tire tread TT.The rearwardly projecting end 131 of the driven shaft 125 projectsthrough the side channel 115 rearwardly thereof and mounts the drivenpulley 132 thereon as best seen in FIG. 2. A buffer drive motor 134(FIGS. 3 and 4) is mounted between the side channels 115 on the bufferarm assembly 110 below the tie bar 118. The buffer drive motor 134 ismounted on the motor support angles 26 on the base frame 11 as best seenin FIGS. 3 and 4 so that its drive shaft 135 is centered on the bufferarm pivot axis A_(BA). The drive shaft 135 projects rearwardly throughthe back side channel 115 as best seen in FIG. 3 and mounts a drivepulley 136 thereon as best seen in FIGS. 2 and 3. A drive belt 138connects the drive pulley 136 with the driven pulley 132 as best seen inFIG. 2 and tension is maintained thereon by the tension assembly 139.Thus, it will be seen that the drive motor 134 rotates the buffing rasps128 counterclockwise as seen in FIG. 6 at a high rate of speed, and,when the buffing surfaces 130 on the buffing rasps 128 come into contactwith the tire tread TT, they remove portions of the tire tread adjacentthe shoulders.

The spacer assembly 112 as best seen in FIGS. 5 and 6 serves toselectively maintain the buffing surfaces 130 of the buffing rasps 128closely adjacent the tire tread TT as seen in FIG. 5 until it isdesirable to force the buffing surfaces 130 into contact with the tiretread to selectively grind away portions thereof. The spacer assembly112 includes a spacer support arm 140 which is mounted on the back plate116 just below the driven shaft 125 of the buffer head assembly 111, inalignment with the central tire tread plane P_(VT) and generally normalto the back plate 116. The spacer support arm 140 includes a pair ofspaced apart generally parallel side plates 141 that are parallel to thetread plane P_(VT) and which are mounted on the back plate of the bufferarm assembly 110 by a base plate 142. The inboard ends of the sideplates 141 are connected by end plate 144. Roller arm 145 is pivotallymounted between the side plates 141 adjacent the inboard end thereof ona pivot shaft 146. The upper end of the roller arm 145 is provided withsupport tabs 148 which rotatably mount a tread engaging spacer roller149 therebetween about roller axis A_(R). It will be noted that theroller axis A_(R) and the roller arm pivot axis A_(RA) are both parallelto the rotational axis A_(BH) of the buffer head assembly 111. The lowerend of the roller arm 145 projects below the spacer support arm 140 aswill become more apparent. A positioning link 150 is pivoted between theside plates 141 just outboard of the roller arm 145 on a drive shaft 151about axis A_(PS) parallel to the buffer head rotational axis A_(BH). Adrive link 152 is also pinned between the side plates 141 outboard ofthe positioning link 150 about a drive link pivot axis A_(DL) which isparallel to the arm axis A_(RA) and the drive shaft axis A_(PS). Thepositioning link 150 and the drive link 152 are maintained parallel toeach other as they pivot by transfer link 154 pinned between positioninglink 150 and the drive link 152 equal distances along the positioninglink 150 and the drive link 152 from their pivot axes A_(DL) and A_(PL).It will be noted that the drive link 152 extends past the transfer link154 and the projecting end 155 of the link 154 is connected to one endof an expansion coil spring 156 whose other end is connected to thelower end of the roller arm 145. It will thus be seen that the coilspring 156 serves to urge the spacer roller 149 away from the drivenshaft 125 and inboard toward the tire assembly TA until the spring 156is completely relaxed. The drive shaft 151 connected to the positioninglink 150 extends laterally out through the front side channel 115 and isconnected to a positioning handle 158 which extends up over the top ofthe side channel 115. The positioning handle 158 is shown by solid linesin FIG. 5 and phantom lines in FIG. 6. A notched guide plate 159 ismounted on the upper end of the front side channel 115 and is providedwith adjustment notches 160 which engage the positioning handle 158 asbest seen in FIG. 5. It will be noted that the positioning handle 158 issufficiently flexible to be positioned in any of the adjustment notches160 and that the coil spring 156 is urging the top of the positioninghandle 158 outboard of the machine or clockwise as seen in FIG. 6 sothat the positioning handle 158 will be maintained in the appropriateadjustment notch 160, especially when the spacer roller 149 is engagingthe tire tread TT as seen in FIGS. 5 and 6. The movement of the spacerroller 149 inboard away from the driven shaft 125 carrying the buffingrasps 128 is limited by an adjustable stop screw 161 in the end plate144 in FIG. 6. The amount of force exerted on the tire tread TT by thespacer roller 49 is thus adjusted by movement of the positioning handle158 into a selected one of the adjustment notches 160. This allows themachine to be adjusted to handle tire treads TT that have a differentcross sectional curvature thereacross as will become more apparent.

The buffer arm positioning assembly 114 is best seen in FIGS. 3, 4 and10 and includes double acting fluid cylinder 165 which is pinned toattachment tab 166 centrally located on top of the tie bar 118. Theprojecting end of the piston rod 168 of the fluid cylinder 165 is pinnedto an attachment tab 169 centrally located on top of the back channel 72on the loading arm assembly 60. It will thus be seen that, as the pistonrod 168 is retracted into the fluid cylinder 165, the buffer armassembly 110 will be pivoted counterclockwise as seen in FIGS. 4 and 10inwardly toward the tire tread to cause the buffing rasps 128 to engagethe tire tread TT as seen in FIG. 6. As the piston rod 168 is extendedfrom the fluid cylinder 165, the buffer arm assembly 110 will be rotatedclockwise to move the buffer head assembly 111 outwardly away from thetire tread TT as best seen in FIG. 4. An expansion coil spring assembly170 is also connected between the attachment tabs 166 and 169 toselectively urge the buffer arm assembly 110 counterclockwise as seen inFIGS. 4 and 10 to move the buffer spacer assembly 112 into contact withthe tire tread TT. The expansion coil spring assembly 170 includes oneor more expansion coil springs 171. While different numbers of coilsprings 171 may be used, two coil springs 171 are illustrated. The coilsprings 171 exert a force on the buffer arm assembly 110 where themagnitude of the force decreases as the buffer head assembly 111 movestoward the tire tread TT. On the other hand, once the spacer roller 149engages the tire tread TT so that the tire tread TT forces the spacerroller 149 clockwise about the roller arm axis A_(RA) as the buffer armassembly 110 continues to pivot toward the tire tread TT, the forceexerted on the buffer arm assembly 110 by the spacer assembly spring 156increases in magnitude. The coil springs 171 of the coil spring assembly170 on the positioning assembly 114 and the spring 156 on the spacerassembly 112 are sized so that the decreasing positioning force exertedon the buffer arm assembly 110 by the springs 171 reaches a magnitudeequal to the magnitude of the increasing spacing force exerted on thebuffer arm assembly 110 by the spring 156. At this neutral point, thenet force on the buffer arm assembly 110 is zero and the opposed forcesby the springs 156 and 171 neutralize each other to stop the movement ofthe buffer head assembly 111 toward the tire tread TT. The positioninghandle 158 is adjusted so that this neutral position which is shown inFIG. 5 is reached when the buffing surfaces 130 of the buffing rasps 128and buffing head assembly 111 are closely adjacent to the tire tread TTbut not actually touching it. Usually, this spacing is about one-fourthof an inch. Because the cross-sectional curvature of the tire tread TTmay change from tire to tire, the actual neutral position of the rollerarm 145 may have to be changed by manipulating the positioning handle158 to maintain the neutral spacing between the buffing surfaces 130 andtire tread TT.

When it is desirable to cause the buffing surfaces 130 on the buffingrasps 128 to engage the tire tread to remove a portion of the shouldersthereof, the full operating pressure of the working fluid from anappropriate source (not shown) is applied to the fluid cylinder 165 toretract the piston rod 168. While the working pressure may vary, usuallythe working fluid pressure is around 100-120 psi. This generates agrinding force on the buffer arm assembly 110 greater than the reactivespacing force applied by the spacer assembly 112 so that this greatergrinder force urges the buffer arm assembly 110 counterclockwise as seenin FIG. 4 against the action of the spring 156 in the spacer assembly112 to cause the buffing surfaces 130 to engage the tire tread TT alongits opposite shoulders as shown in FIG. 6. It will be noted that theamount the buffer arm assembly 110 can rotate counterclockwise under theforce of the fluid cylinder 165 is limited only by engagement of thebuffing rasps 128 with the tire tread TT and that the grinding rasps 128are urged into contact with the tire tread TT at a substantiallyconstant force. When it is desirable to move the buffing rasps 128 outof engagement with the tire tread TT, the working fluid pressure on thefluid cylinder 156 is released and the spring 156 in the spacer assembly112 urges the buffer arm assembly 110 clockwise back to the neutralposition seen in FIG. 5 where the force of the spring 156 neutralizesthe force of the coil springs 171.

ALTERNATE SPACER ASSEMBLY

FIGS. 7-9 illustrate an alternate spacer assembly which has beendesignated generally by the numeral 112'. This spacer assembly 112'operates in general principal similar to the spacer assembly 112. Thespacer assembly 112' comprises generally a support housing 176 mountedon the back plate 116 just below the driven shaft 125 carrying thebuffing rasps 128 and projects generally normal to the backing plate 116and perpendicular to the buffing axis A_(BH). The spacer assembly 112'is likewise centered under the driven shaft 125. The support housing 176includes a mounting plate 178 mounted on the back plate 116 of thebuffer arm assembly 110 and a tubular wall 179 (FIG. 9) generallyrectilinear in cross-section which defines a positioning chamber 180therein opening on the inboard end of the tubular wall 179. Apositioning housing 181 (FIG. 9) is sized for slidable receipt in thepositioning chamber 180 in the support housing 176 and also includes atubular side wall 182 generally rectilinear in cross-sectional shape.The side wall 182 of the positioning housing 181 defines a spacerchamber 184 therein which opens onto the inboard end of the positioninghousing 181 and which is closed at the outboard end of the positioninghousing 181 by an attachment plate 185 as best seen in FIG. 9. Theattachment plate 185 is rotatably connected to an adjustment screw 186so that the positioning housing 181 will be axially moved along thepositioning axis A_(PH) which is the common centerline of the housing176 and housing 181. The adjustment screw 186 is externally threaded andextends through the mounting plate 178 on the support housing 176 whichis complimentary internally threaded so that, as the adjustment screw186 is rotated, the positioning housing 181 will be axially moved withinthe support housing 176. A positioning handle 188 is carried on theadjustment screw 186 on the outboard end thereof projecting through theback plate 116 so that the adjustment screw 186 can be manually rotated.Spacer bar 189 having a generally rectilinear cross-sectional shape isslidably received in the positioning housing 181 for reciprocal movementalong the axis A_(PH). The axial movement of the spacer bar 189 iscontrolled by an abuttment pin 190 best seen in FIGS. 8 and 9 whichextends through the spacer bar 189 at the outboard end thereof and whichis slidably received in opposed elongate slots 191 in the tubular sidewall 182 of positioning housing 181. This allows the spacer bar 189 tomove the distance d_(SB) seen in FIG. 9 with respect to housing 181. Theabuttment pin 190 is sized so that the positioning housing 181 canslidably move within the support housing 176 without interferencetherewith. A compression coil spring 192 is positioned in the spacerchamber 184 between the outboard end of the spacer bar 189 and theattachment plate 185 on the outboard end of the positioning housing 181while the inboard end of the spacer bar 189 is provided with a pair ofupstanding support tabs 194 that mount the spacer roller 149 at theupper end thereof about roller axis A_(R) which is generally parallel tothe buffer axis A.sub. BH. Thus, it will be seen that, when the spacerroller 195 contacts the tire tread TT, the spacer bar 189 will be forcedinto the positioning housing 181 as the buffer head assembly 111 ismoved toward the tire tread TT. This causes the inboard end of thespacer bar 189 to compress the coil spring 192 to generate the reactiveforce enumerated hereinabove to offset the closing force on the bufferarm assembly 110 by the coil springs 171 in the buffer arm positioningassembly 114. This likewise causes a neutral point to be reached whichis illustrated in FIG. 7 so that the tire tread TT is closely adjacentbut not engaging the buffing surfaces 130 on the buffing rasps 128. Thefully extended position of the spacer roller 149 is shown by a phantomline in FIG. 7 while the position of the spacer roller 149 is shown inbuffing position in FIG. 7 by a dashed line. The overriding of thespring 192 by the fluid cylinder 165 is the same as that describedhereinbefore.

It will be noted that the relative positions of the attachment tab 166on the buffer arm assembly 110 and the attachment tab 169 on the loadingarm assembly 60 as best seen in FIG. 10 are located such that, as theloading arm assembly 60 is pivoted clockwise as seen in FIG. 10, theattachment tab 169 is moved along a pivot path P_(PA) which causes thebuffer arm assembly 110 to be moved inwardly when the connection betweenthe piston rod 168 and springs 171 on attachment tab 169 are raisedabove horizontal alignment with the connection between the fluidcylinder 165 and the coil springs 171 on the attachment tab 166. Thisallows the machine to be used on different size tires withoutappreciably effecting the operation of the machine since the furtherclockwise movement of the loading arm assembly 60 from the position seenin FIG. 10 when a smaller diameter tire T is on the machine causes thebuffer arm assembly 110 to be automatically pivoted furthercounterclockwise inwardly toward the tire tread TT. This always assuresthat the coil spring assembly 170 in the buffer arm positioning assembly114 will operate to maintain the spacer assembly 175 or 112 in contactwith the tire tread TT.

It will be noted in FIG. 10 that the buffing rasps 128 in the bufferhead assembly 111 engage the tire tread TT at a buffing position P_(B)that is angularly shifted through the angle φ from the loading positionP_(L) of the loading drum 62. It will also be noted that the effectivelength L_(A) of theloading arm assembly 60 and the effective lengthL_(BA) of the buffing arm assembly 110 are about equal to each other andare considerably greater than the radius of the tires T with which themachine is to be used. Usually, the effective lengths L_(LA) and L_(BA)are at least about twice the radius of the maximum size tires T withwhich the machine is to be used. It will further be noted that thedistance L_(LP) from the drive spindle axis A_(DS) to the loading armpivot axis A_(DA) is about equal to the distance L_(BP) between thedrive spindle axis A_(DS) and the buffing arm pivot axis A_(BA). Theloading arm pivot axis A_(DA) is located outboard of and intermediate acommon flat buffing arm plane P_(BA) (FIG. 10) extending through buffingunit axes A_(BH) and A_(BA). The axis A_(DA) is also parallel to planeP_(BA). The buffer arm pivot axis A_(BA) is located outboard of andintermediate a common flat loading arm plane P_(LA) (FIG. 10) extendingthrough loading pivot axis A_(DA) parallel to the upper edges of armside members 68. The axis A_(BA) is also parallel to plane P_(LA), andthe drum axis A_(D) is both parallel to and movable toward and away fromplane P_(LA).

It will be appreciated that the spring 156 in the spacer assembly 112and/or the spring 192 in the spacer assembly 112' can be replaced withany device which exerts a varying reactive force between the buffer armassembly 110 and the tire tread TT where the spacing force increases asthe buffer head assembly 111 moves toward engagement with the tire treadTT. An example of such device would be a closed cylinder with its pistonrod acting against a compressible liquid. The spring assembly 170 in thepositioning assembly 114 may likewise be replaced with any device whichexerts a varying positioning force moving the buffer arm assembly 110toward the tire tread TT where the positioning force decreases as thebuffer head assembly 111 moves toward engagement with tire tread TT. Asa matter of fact, as long as either the spacing force or the positioningforce varies as set forth above, the other force may be constant as longas the neutral point is reached with the buffing rasps 128 closelyadjacent to but out of engagement with the tire tread TT.

TIRE BALANCING MACHINE

The overall tire balancing machine is best seen in FIG. 18. The tirebalancing machine 300 is commonly known as a two-plane balancer. Thismachine is a computerized balancer that dynamically balances tireassembly TA by electronically individually balancing opposed sides ofthe tire assembly TA. The machine 300 has a driving unit 301 which spinsthe wheel assembly TA for balancing. The driving unit 301 shown hereinhas a balancer drive spindle 302 as seen in FIGS. 19-21 rotatable aboutbalancer spindle axis A_(BS) which mounts the adapter 54 with the tireassembly TA so that the central axis of adapter 54 coincides with thespindle axis A_(BS).

The drive spindle 302 has an abuttment 304 (FIGS. 19-21) adjacent itsinboard end. That portion of spindle 302 outboard of abuttment 304defines an exterior cylindrical adapter support surface 305 thereonconcentric about the spindle axis A_(BS) and with diameter d_(DS) (FIG.21). The support surface 305 has an effective length L_(BS) (FIG. 21) aswill become more apparent. The outboard end of the balancer spindle 302has a reduced diameter, externally threaded engagement section 306thereon to threadedly receive an internally threaded locking nut 308thereon. The locking nut 308 defines a tapered cone surface 309 on theinboard end thereof (FIG. 20) which positively locates adapter 54 aswill become more apparent and defines external wrenching surfaces 307 totighten same.

A balancer drive key 310 (FIGS. 19-21) is mounted on spindle 302 justoutboard of abuttment 304 and projects outwardly through the supportsurface 305. The drive key axis A_(BK) (FIG. 21) is parallel to spindleaxis A_(BS) and has a length L_(BK). The drive key 310 has a constantexposed height H_(BK) (FIG. 19) along its length but its side edges 311taper outwardly from a minor width W_(B1) (FIG. 21) at the outboard end312 of key 310 to a major width W_(B2) (FIG. 21) at its inboard end 314as will become more apparent. The key 310 may be held in place by a rollpin 315 (FIG. 21). The drive key 310 operates in conjunction with nut308 to positively locate adapter 54 on spindle 302 as will become moreapparent.

TIRE MOUNTING ADAPTER

The tire assembly mounting adapter 54 is best seen in FIGS. 12-16 andserves to accurately locate the tire assembly TA alternatively on thebuffer drive spindle 40 of buffing machine 10 (FIGS. 10 and 11) or onthe balancer drive spindle 302 of the balancing machine 300 (FIGS. 18and 19). In either case, the tire assembly TA is mounted so that itsvehicle effective rotational axis coincides with the buffer spindle axisA_(DS) of buffer drive spindle 40 or the balancer spindle axis A_(BS) ofthe balancer drive spindle 302 and positively connects the tire assemblyTA to buffer drive spindle 40 or balancer drive spindle 302. Themounting adapter 54 is mounted on the tire assembly TA before it isplaced in the buffing machine 10 and/or balancing machine 300 since tireassemblies are relatively heavy, up to 100 lbs. normally, and can bemuch more easily positioned while they are not on the machines 10 or300.

The mounting adapter 54 includes a support sleeve 210 (FIG. 12) which isalternatively received on the buffer drive spindle 40 of buffing machine10 or balancer drive spindle 302 of balancing machine 300 to support thetire assembly TA and a locking nut 211 which holds the tire assembly TAon the support sleeve 210. A number of different wheel positioningassemblies 212 may be used with the support sleeve 210 and locking nut211 to mount different kinds of wheel rims WR on the support sleeve 210.One type of wheel positioning assembly 212 is illustrated in FIGS. 12-14and another type of wheel positioning assembly 212' is illustrated inFIGS. 15 and 16.

The support sleeve 210 includes a tubular side wall 214 with a centralaxis A_(MA) which defines a central passage 215 therethrough concentricabout axis A_(MA) with a diameter d_(AS) substantially equal to thediameter d_(DS) of both the spindle 40 of buffing machine 10 and spindle302 of balancing machine 300 so that the sleeve 210 will be slidablyreceived over the spindle 40 or the spindle 302. The central passage 215opens on opposite ends of the side wall 214. The inboard end of the sidewall 214 is integral with an outwardly projecting arresting flange 216to arrest the movement of the wheel positioning assemblies 212 and 212'along the outside bearing surface 218 of the side wall 214. Thearresting flange 216 is oriented normal to the adapter axis A_(MA). Thearresting flange is provided with a locating pin 219 extendingtherethrough generally parallel to the adapter axis A_(MA) andprojecting from the arresting flange 216 outwardly along the tubularside wall 214. The inboard end of the tubular side wall 214 isexternally threaded with threads 220 to be threadedly engaged by thelocking nut 211 as will be explained. The side wall 214 is provided witha key slot 221 that extends axially thereof and opens into the centralpassage 215 as best seen in FIGS. 12-14. The key slot 221 has a constantwidth W_(KS) (FIGS. 14 and 20) along its length and a depth D_(KS)(FIGS. 12 and 19) along its length. The slot 221 is positively engagedby key 58 on buffer drive spindle 40 and by key 310 on balancer drivespindle 302 to positively connect adapter 54 and thus tire assembly TAto the spindle 40 or 302 so that the tire assembly TA will be positivelyrotated therewith. The width W_(KS) is about equal to the width W_(DK)of buffer key 58 so that the support sleeve 210 can be slipped over thebuffer drive spindle 40 with the central passage 215 in support sleeve210 over spindle 40 and the drive key 58 projecting into key slot 221 tocause the drive spindle 40 to positively drive the support sleeve 210.

It will further be seen in FIGS. 20 and 21 that the width W_(KS) of keyslot 221 is greater than the outboard minor width W_(B1) of the balancerkey 310 on balancer drive spindle 320 but less than it inboard majorwidth W_(B2). When support sleeve 210 is slipped over the balancer drivespindle 302 with the central passage 215 in support sleeve 210 about thesupport surface 305 on spindle 302 (FIG. 20), the inboard end 312 ofbalancer drive key 310 will extend into slot 221. Because the inboardwidth W_(B2) is wider than slot 221, however, opposite sides of slot 221will wedge onto the outwardly flared side edges 311 (FIG. 20) to arrestthe movement of sleeve 210 and prevent any loose motion between theinboard end of sleeve 210 and balancer spindle 302. It will further benoted in FIG. 20 that the outboard end of sleeve 210 is provided with atapered countersink surface 213 about the end of central passage 215through sleeve 210. The countersink surface 213 is complimentary to thecone surface 309 on balancer locking nut 308 so that when balancerlocking nut 308 is screwed onto the engagement section 306 on balancerspindle 302 (FIG. 20), the cone surface 309 on nut 308 engagescountersink surface 213 on sleeve 210 to maintain the outboard end ofsleeve 210 concentric with spindle axis A_(BS) and the balancer key 310in engagement with slot 221 in sleeve 210. This locks sleeve 210 ontospindle 302 with the sleeve axis A_(MA) coinciding with spindle axisA_(BS) (FIG. 20). The outside bearing surface 218 on support sleeve 210has an outside diameter d_(SS). This outside bearing surface 218 isconcentric about the sleeve axis A_(MA) and slidably mounts thepositioning assembly 212 or 212' thereon.

The locking nut 211 is internally threaded as seen in FIG. 12 with nutthreads 222 sized to threadedly engage the threads 220 on the outboardend of the support sleeve 210 so that the locking nut 211 can be screwedonto the outboard end of the support sleeve 210. The locking nut 211 isprovided with a pair of outwardly extending forwardly angled handles 224so that the handle 224 can be manually grasped to screw the locking nut211 onto the support sleeve 210 quickly and easily.

The wheel positioning assembly 212 seen in FIGS. 12-14 includes a backupplate 225, spring washer 226, a locating cone 228 and a clamp ring 229.The backup plate 225 is a cup shaped member which has a circular inboardend wall 230 integral with a cylindrical extending edge flange 231 alongits outboard edge concentric with axis A_(MA). The edge flange 231 is inturn integral with an outboard annular flange 232 around its outboardend so that the outboard flange 232 is generally normal to the adapteraxis A_(MA) when the backup plate 225 is positioned on the sleeve 210. Acentral hole 234 is provided through the inboard wall 230 with adiameter d_(SS) so that the backup plate 225 will be slidably receivedonto the outside bearing surface 218 of the support sleeve 210. Alocating hole 235 is also provided through the inboard wall 230 which isregistrable with the locating pin 219 in the arresting flange 216 on thesupport sleeve 210 so that the backup plate 225 is positively connectedto the support sleeve 210. An outboard locating recess 236 is bounded byinboard end wall 230 and the edge flange 231 with a prescribed depthd_(LS) as will become more apparent.

The spring washer 226 is an annular spring member with an offset thereinso that the washer will exert an axial force along the adapter axisA_(MA) when it is placed on the support sleeve 210. The spring washer226 is positioned in the locating recess 236 so that it bears againstthe outboard side of the inboard wall 230 as seen in FIG. 13.

The locating cone 228 is an annular member defining a locating hole 238centrally therethrough with a diameter d_(SS) slidably receiveable overthe bearing surface 218 of the support sleeve 210. The locating cone 228defines a tapered locating surface 239 therearound concentric about theaxis A_(MA) which tapers inwardly from a maximum diameter d_(MX) at itsinboard end to a minimum diameter d_(MN) at its outboard end. Thelocating cone 228 is positioned on the support sleeve 210 so that itsinboard end rests on the spring washer 226 as seen in FIG. 13. When thewheel rim WR is positioned adjacent the outboard surface of the backupplate 225 with its central opening CO through the central disk CD aroundthe locating surface 239 on the locating cone 228 as seen in FIG. 13,the locating surface 239 will locate the wheel by the central opening COso that the effective rotational axis of the tire assembly TA coincideswith the adapter axis A_(MA) if the central opening CO in the wheel rimWR is at its true center. Different size cones 228 are normallyprovided.

The clamp ring 229 includes an annular side wall 240 concentric aboutthe axis A_(MA). A central web 241 is integral with the side wall 240intermediate its ends and arranged normal to the axis A_(MA) so as toform a cone recess 242 in the inboard end of the clamp ring 229 and anut recess 244 in the outboard end of the clamp ring 229. The centralweb 241 defines a locating hole 245 therethrough with diameter d_(SS) tobe carried on the support sleeve 210. The outboard end of the side wall240 is integral with an annular outwardly directed flange 246 generallynormal to the axis A_(MA). This allows the clamp ring 229 to be reversedto clamp different size wheel rims WR onto the adapter 54.

As seen in FIG. 13, the clamp ring 229 is slipped over the supportsleeve 210 so that the inboard end thereof engages the outboard side ofthe wheel rim WR about the central opening CO and then the locking nut211 is screwed onto the threads 220 on the support sleeve 210 to urgethe clamp ring 229 toward the backup plate 225. The spring washer 226and the maximum and minimum diameters d_(MX) and d_(MN) of the locatingsurface 239 on the locating cone 228 are sized so that the locatingsurface 239 on the cone 228 will engage the central opening CO throughthe wheel rim before the clamp ring 229 forces the inboard side of thewheel rim WR into contact with the outboard side of the backup plate225. Thus, it will be seen that the locating surface 239 maintainscentral opening CO concentric about the adapter A_(MA) so that when theadapter 54 with the tire assembly TA mounted thereon is slipped over thebuffer drive spindle 40 as seen in FIG. 13 or the balancer drive spindle302 as seen in FIG. 19, the tire assembly TA will be mounted with itseffective rotational axis concentric with the buffer spindle axis A_(DS)or the balancer spindle axis A_(BS). The stop collar 55 on bufferspindle 40 is adjusted so that the central tread plane P_(VT) of thetire assembly TA is laterally aligned with the center of the drivenshaft 125 on the buffer unit 15 seen in FIG. 5 which also aligns theplane P_(VT) with the midpoint of the loading drum 62 on the loadingunit 14 seen in FIG. 11.

Where the central opening CO through the central disk CD Of the wheelrim WR is not concentric about the true rotational axis of the tireassembly TA, the wheel positioning assembly 212' illustrated in FIGS. 15and 16 may be used. It will be noted that the lug holes LH (FIG. 13) inthe wheel rim WR are always concentrically located about the effectiverotational axis of the tire assembly TA and these lug holes LH are usedto mount the wheel rim WR on the support sleeve 210 by the positioningassembly 212'. The positioning assembly 212' includes a pair of slotadapter plates 250 and a plurality of adapter studs 251 which cooperatewith the slot adapter plates 250 to locate the tire assembly TA on thesupport sleeve 210 and are held in position by the locking nut 211.

Each of the slot adapter plates 250 is circular and is provided with acentral locating hole 252 of diameter d_(SS) so that when both of theplates 250 are slidably received on the support sleeve 210, they areoriented generally normal to the adapter axis A_(MA) and concentrictherewith. Each adapter plate 250 with a first set of radially extendedslots 254 and a second set of radially extending slots 255. The slots254 are used to mount a four lug wheel rim wheel the slots 255 are usedto mount a five lug wheel rim. Thus, the slots 254 are located 90° apartwhile the slots 255 are located 72° apart. Other than the spacing, theslots 254 and 255 are identical. Each of the slots 254 and 255 have aneffective length L_(RS) and are centered on a circular path P_(RS) sothat the slots 254 and 255 can be aligned with any lug hole circle onthe wheel rim WR.

The adapter studs 251 each have a locating projection 256 on the inboardend thereof with flat sides thereon so that the studs 251 are preventedfrom turning when they project through the slots 254 or 255 in theinboard adapter plate 250. Immediately outboard of the locatingprojections 256 is a tapered locating section 258 which engages thetapered lug hole LH in the wheel rim WR. Each stud 251 includes acylindrical main body 259 immediately outboard of the locating section258. The outboard end of the main body 259 is provided with a threadedmounting section 260 which also has flattened sides so that when thesections 260 are provided through the slots 254 or 255 in the outboardplate 250, the studs 251 are prevented from rotating. Appropriate nuts261 may be provided to threadedly engage the mounting sections 260 tolocate the studs 251 on the outboard plate 250 are illustrated in FIG.16. It will also be noted that at least the inboard adapter plate 250 isprovided with a locating hole 262 which positively connects the inboardplate 250 to the support sleeve 210 by the locating pin 219. Thus, whenthe wheel rim WR is placed on the outboard side of the inboard adapterplate 250 and rotated so that the lug holes LH line up with the slots254 or 255, the studs 251 can then be inserted through the lug holesinto the slots 254 or 255 in the inboard adapter plate 250 inregistration with the lug holes LH. The studs 251 may either be alreadyattached to the outboard plate 250 or outboard plate 250 subsequentlyattached thereto. This inherently centers the tire assembly TA about theadapter axis A_(MA) so that the effective rotational axis of the tireassembly TA coincides with the adapter axis A_(MA) and will coincidewith the buffer spindle axis A_(DS) when the adapter 54 with the tireassembly TA mounted thereon is placed on the buffer spindle 40 or withthe balancer spindle axis A_(BS) when the adapter 54 with tire assemblyTA mounted thereon is placed on the balancer spindle 302.

CONTROL CIRCUIT

The machine 10 is controlled by a control circuit CC best seen in FIG.17. The inputs to the control circuit CC are provided by thedisplacement transducer 95 on the loading unit 14 and a touch keyboardTK. The keyboard TK includes a stop switch STP, a start switch STS and amode selector switch MSS. The output of the transducer 95 is connectedto a lock point detector LPD, a linear summer LS and a low referencehold LRH. The output of the lock point detector LPD is connected to amode timing generator MTG and to the lock solenoid Sol-L on the loadingcylinder lock valve V-LC. The output of the linear summer LS isconnected to a buff comparator BC, a reject comparator RC and a radialrunout display RRD to visually indicate the amount of loaded radialrunout. The output of the low reference hold LRH is also connected tothe linear summer LS. The start switch STS and stop switch STP control arun latch RL. The mode selector switch MSS and start switch STS controla mode latch ML. The lock point detector LPD is controlled by a loadreference LR and the reject comparator RC is controlled by a fixedreject limit FRL. One output (6 revolutions) of the mode timinggenerator MTG is connected to a buff level network BLN, to a decoderdriver DD and to a time delay network TDN. Another output (3revolutions) of the mode timing generator MTG is connected to the bufflatch BL and the reject latch RTL. Another output (3-5 minutes) of themode timing generator MTG is connected to a control gate CG. The bufflevel network BLN is controlled by the outputs of the mode latch ML toset the radial runout level to which the tire assembly is to be buffed.The "over buff" output from latch ML may also drive an "over buff" lampOBL and the "fine buff" output of latch ML may also drive a "fine buff"lamp FBL. The output of the buff level network BLN controls the buffcomparator BC through buff level inhibit network BLT. The output of thereject comparator RC controls the reject latch RTL. The output of thebuff comparator BC is connected to the buff latch BL, a revolution timerRT and time delay network TDN. The output of the buff comparator BC alsoprovides the control feedback to network BLI. The output of the timedelay network TDN is connected to the buff solenoid Sol-B on the buffingcylinder valve V-BC and also provides the enabling control signal tobuff level inhibit network BLI. The output of the revolution timer RT isconnected to the reset inputs on the buff latch BL and the reject latchRTL. The outputs of the buff latch BL and reject latch RTL control theoutput state of the decoder driver DD. The "reject" output of thedecoder driver DD is connected to the control gate GG and may control a"reject" lamp RJL. The "buff" output of the decoder driver DD maycontrol a "buff" lamp BFL. The "good" output of the decoder driver DD isconnected to the control gate CG and may control a "good" lamp GL. Theoutput of control gate CG controls the run latch RL. The output of therun latch RL controls the run solenoid Sol-R of the run valve V-R tosupply pressure to valve V-LC and V-BC, and also controls the motorcontrol relay MCR. A manually operable unload switch US may be connectedto the unloading solenoid Sol-U on a buffer unloading valve V-UB toextend piston rod 168 on cylinder 165 to insure that the buffer unit 15is fully open. Usually, the geometry of the loading arm pivot A_(DA) andbuffer arm pivot A_(BA) is such that the opening of loading unit 14opens buffer unit 15 sufficiently in order that valve V-UB need not beused.

OPERATION

In operation, it will be seen that the operator mounts the tire assemblyTA on the adapter 54 while the adapter is off of machine 10 so that theeffective rotational axis of the tire assembly TA coincides with theadapter central axis A_(MA) (FIGS. 13 and 15). After the tire assemblyTA is mounted on the adapter 54, the operator slides the adapter 54 withtire assembly TA thereon onto drive spindle 40 with the inboard end ofsleeve member 210 first until the inboard end of sleeve member 210contacts the locking collar 55 (FIGS. 11 and 13). The locking collar 55has been adjusted so that the tire assembly TA is positioned as seen inFIGS. 10 and 11.

The operator now depresses the start switch STS which starts theautomatic operation of machine 10. Closing switch STS enables the runlatch RL thereby energizing the solenoid Sol-R and transfers valve V-Rto supply fluid under pressure to the closed end of load cylinder 100through lock valve V-LC. This extends piston rod 102 from load cylinder100 to pivot loading arm assembly 60 clockwise as seen in FIG. 10 toraise the loading drum 62 into contact with the tire tread TT as seen inFIGS. 10 and 11. At the same time, run latch RL closes the motor controlrelay MCR (FIG. 17) to start the spindle drive motor 49 in drive unit 12(FIG. 11) and the buffer drive motor 134 in the buffer unit 15 (FIG.10). Motor 49 starts rotating the tire assembly TA counterclockwise inFIG. 10 at a prescribed speed, usually about 15-20 rpm through the key58 on drive spindle 40 and the drive pin 219 (FIG. 13) on the sleevemember 210 of adapter 54 while motor 134 rotates the buffing rasps 128counterclockwise as seen in FIG. 10 at a sufficient speed to properlybuff the tire tread, usually about 3000-4000 rpm. The tire tread TTurges the drum 62 and yoke assembly 61 counterclockwise upon contact ofdrum 62 with tread TT as seen in FIG. 10 as the loading arm assembly 60continues to move clockwise in FIG. 10. This compresses springs 91 inspring assembly 90 and eventually moves the drive pin 98 on yokeassembly 61 into engagement with the operating plunger 96 on transducer95 to move plunger 96 downwardly in FIGS. 10 and 11 and generate anappropriate output from transducer 95. When the output of the transducer95 reaches the preset output of the load reference LR (usually about0.07 inch plunger 98 movement) (FIG. 17), the lock point detector LPDchanges state to energize lock solenoid Sol-L and transfer the lockvalve V-LC so that the fluid in cylinder 100 is locked therein. The loadunit 14 is now in the position seen in FIGS. 10 and 11.

The clockwise movement of loading arm assembly 60 also pivots the bufferarm assembly 110 counterclockwise inwardly toward the tire as seen inFIG. 10 so that the spacer roller 149 in spacer assembly 112' engagesthe tire tread TT. When the tire tread TT engages the roller 149 onspacer assembly 112' tread TT prevents further movement of the roller149 with the buffer arm assembly 110 toward the tire tread. The contactbetween the tire tread TT and roller 149 occurs prior to the loading armassembly 60 reaching its locked loaded position seen in FIG. 10. As theloading arm assembly 60 continues to move clockwise in FIG. 10 towardits loaded position, the spring assembly 170 in positioning assembly 114connecting the buffer arm assembly 110 with the loading arm assembly 60moves the buffing arm assembly 110 further toward the tire tread TT. Asthe coil spring assembly 170 continues to move the buffer arm assembly110 counterclockwise as seen in FIG. 10, the tire tread TT forces thespacer bar 189 into the positioning housing 181 on spacer assembly 112'to compress spring 192 (FIG. 9) in housing 181 and generate a reactiveforce trying to force the buffer arm assembly 110 clockwise away fromthe tire tread TT. Because this reactive force increases as the bufferarm assembly 110 moves toward the tire tread TT to further compress thespring 192 in spacer assembly 112', a neutral position (FIGS. 7 and 10)will be reached when the loading arm assembly is in its locked positionwhere the reactive force on buffer arm assembly 110 by the spacerassembly 112' equals the closing force on buffer arm assembly 110 by thespring assembly 170 in positioning assembly 114. The movement of thebuffer arm assembly 110 thus stops in this neutral position as long asthe closing and reactive forces on the buffer arm assembly remain equal.The position of housing 181 with respect to support housing 176 ofspacer assembly 175 is adjusted via handle 188 (FIG. 10) so that thebuffing surfaces 130 on buffing rasps 128 are located closely adjacentto, but not in engagement with, the shoulders on the tire tread TT whenthe neutral position is reached (FIGS. 7 and 10). The spacer assembly112 (FIGS. 5 and 6) would also position the rasps 128 in a similarneutral position.

The tire assembly TA is now radially loaded by the loading drum 62 andthe buffer unit 15 is in neutral position ready for buffing. Because theloading drum 62 is freely rotatable about axis A_(D), the drum 62 canrotate with tread TT as tire assembly TA is positively driven by thedrive unit 12 to rotate the tread TT first past the loaded point P_(L)and then past the buffing point P_(B) (FIG. 10). While different radialloads may be applied to the tire assembly TA by loading unit 14, about a1,000 pound load usually approximates the radial load on the tireassembly TA when it is mounted on a vehicle.

The control circuit CC (FIG. 17) automatically causes the machine tofirst go through a stabilizing period and then through a determinationperiod to determine the state of loaded radial runout in the tireassembly TA. If the circuit determines that the loaded radial runout isin the acceptable range or that the loaded radial runout is in thereject range above the range which can normally be corrected, then themachine 10 is shut down for tire assembly TA to be unloaded with theloading unit 14 and buffing unit 15 returning to their open positions.If, on the other hand, the circuit CC determines that the loaded radialrunout is in the correctable range (i.e. greater than acceptable rangebut less than the reject range), then the circuit CC automatically goesinto the correction period to reduce the loaded radial runout into theacceptable range. For sake of clarity the stabilizing, determination andcorrection periods will be described separately.

STABILIZING PERIOD

The change of state in the output of the lock point detector LPD (FIG.17) when the tire assembly TA becomes radially loaded starts the modetiming generator MTG. At the same time, the output of the transducer 95(FIG. 17) is being fed to the linear summer LS and low reference holdLRH. The signal from transducer 95 to low reference hold LRH drives theoutput from the low reference hold LRH to linear summer LS to the lowestloaded radial runout output from transducer 95 to establish a "zero"reference point. At the drive unit 12 (FIG. 11) continues to rotate tireassembly TA over the loading drum 62, the "zero" output from lowreference hold LRH is subtracted from the output of transducer 95 by thelinear summer LS so that the output of the linear summer LS isrepresentative of the actual loaded radial runout of the tire assemblyTA at the loaded position P_(L). The actual loaded radial runout fromsummer LS is displayed on the radial runout display RRD and is also fedto the buff comparator BC and reject comparator RC.

The buff comparator BC compares the actual radial run-out from linearsummer LS with the buff set point from the network BLN and changes itsoutput state if the actual radial runout exceeds the buff set point togenerate a buff signal output to the buff latch BL. The buff latch BLis, however, disabled by the generator MTG until the tire assembly TAhas rotated about three revolutions after loading to assure accuracy.

The reject comparator RC, on the other hand, compares the actual loadedradial runout from linear summer LS with the reject set point from thefixed reject limit FRL and changes its output state if the actual radialrunout exceeds the reject set point to generate a reject signal outputto the reject latch RTL. The reset latch RTL, however, is also disabledby the generator MTG until the tire assembly TA has rotated about threerevolutions after loading to assure accuracy.

DETERMINATION PERIOD

After the tire assembly TA has rotated about three revolutions, the modetiming generator MTG (FIG. 17) enables both the buff latch BL and thereject latch RTL and the tire assembly TA continues to rotate. If a buffsignal output from buff comparator BC is received by buff latch BL, itis latched to change its output state and generate a buff latch signaloutput to the decoder driver DD. Likewise, if a reject signal outputfrom reject latch RTL, it is latched to change its output state andgenerate a reject latch signal output to decoder driver DD. Until thetire assembly TA has rotated about six revolutions after loading, thedecoder driver DD is disabled by generator MTG.

It will also be noted that each time a buff signal output is generatedby buff comparator BC the revolution timer RT is started and the buffsignal output is fed to time delay network TDN. The revolution timer RTtimes out after about one revolution of the tire assembly TA without abuff signal being generated by comparator BC to reset the latches BL andRTL to prevent over buffing as will become apparent. The time delaynetwork TDN is disabled by generator MTG to prevent buffing of tiretread TT until the tire assembly TA has rotated about six revolutionsafter loading.

After the tire assembly TA has rotated about six revolutions afterloading, the decorder driver DD is enabled by generator MTG. The outputsof the decoder driver DD then change in accordance with the inputsthereto from buff latch BL and reject latch RTL. If no buff latch signaloutput is received from latch BL and no reject latch signal output isreceived from reject latch RTL, then the loaded radial runout of thetire assembly TA is acceptable and the "good" output from decoder driverDD (FIG. 17) changes state to illuminate "good" lamp GL and causecontrol gate CG to disable the run latch RL to shut the machine 10 downand open the loading unit 14 thereby opening the buffer unit 15. If, onthe other hand, a buff latch signal output is received from buff latchBL and a reject latch signal output is received from reject latch RTL,then the loaded radial runout of the tire assembly TA is not readilycorrectable and the "reject" output from decoder driver DD changes stateto illuminate "reject" lamp RJL and cause control gate CG to disable runlatch RL to shut machine 10 down and open the loading unit 14 therebyopening the buffer unit 15. When a buff latch signal output is receivedfrom buff latch BL but no reject latch signal output is received fromreject latch RTL, the "buff" output from the decoder driver DD changesstate to illumitate "buff" lamp BFL to indicate that the tire assemblyTA needs correcting and the loaded radial runout is in the correctablerange. It will be noted that the "buff" output from decoder driver DDdoes not cause the control gate CG to disable run latch RL so that themachine 10 goes into its correction period.

CORRECTION PERIOD

When the decoder driver DD is enabled by the mode timing generator MTG,the generator MTG also enables the time delay network TDN and alsocauses the buff level network BLN to lower its set point output duringthe correction period to assure repeatability. As the tire assembly TAcontinues to rotate, the buff signal output from the buff comparator BCto time delay network TDN is delayed in the time delay network TDN untilthat portion of the tire tread TT at load position P_(L) generating thebuff signal output has rotated to the vicinity of the buff positionP_(B). At that time, the time delay network TDN generates a buff signalto the buff solenoid Sol-B to transfer valve V-BC (FIG. 17). Thisretracts piston rod 168 into cylinder 165 in positioning assembly 114(FIGS. 10 and 17) to force buffer arm assembly 110 counterclockwise inFIG. 10 to overcome the action of spacer assembly 112' and force thebuffing surfaces 130 on rasps 128 into contact with that portion of thetread TT with correctable loaded radial runout now located at buffposition P_(B). It will be noted that the cylinder 165 will apply asubstantially constant buffing force to the buffer arm assembly 110 aslong as the fluid line pressure is about constant and that the depth ofthe buffing of the tread TT by rasps 128 is not controlled. However, thebuffing force is sufficiently low to prevent significant excessivebuffing. When the output of buff comparator BC drops back to its"no-buff" state, this "no-buff" signal output is delayed in time delaynetwork TDN and then de-activates solenoid Sol-B to transfer valve V-BCback to its de-activated position and bleed the fluid from cylinder 165.This allows the spacer assembly 112' and the positioning assembly 114 tomove the rasps 128 and buffer arm assembly 110 back to their neutralposition with the buffing surfaces 130 out of engagement with theshoulders of tire tread TT (FIGS. 7 and 10). This operation is repeatedon each buff signal output from comparator BC.

While the buffing surfaces 130 on rasps 128 (FIG. 10) are forced intobuffing engagement with the tire assembly TA, it has been found that thebuffing force distorts the actual loaded radial runout signal, usuallyby artificially raising the magnitude of the output from transducer 95.This distortion is compensated for by the buff level inhibit network BLI(FIG. 17). The buff signal from the time delay network TDN thatenergizes solenoid Sol-B also causes the buff level inhibit network BLIto raise the buff set point output from buff level network BLN to alevel which offsets the distortion in the actual loaded radial runoutoutput from summer LS and assure accuracy. As the tire tread TT isbuffed sufficiently to approach the acceptable radial runout range, thedistortion in the loaded radial runout output from linear summer LS whenthe rasps 128 engage the tire tread TT may be reduced. This may causethe output of the buff comparator BC to inappropriately change back toits "no buff" state. To prevent this from occuring, the "no buff" outputof the buff comparator BC may be used to disable the buff level inhibitnetwork BLI when it shifts back to its "no buff" state.

The revolution timer RT resets the buff latch BL after a completerevolution of the tire assembly TA without a buff signal output beinggenerated from buff comparator BC. This indicates that the tire assemblyTA has been buffed into the acceptable runout range to cause the decoderdriver DD to terminate its "buff" output and generate a "good" output toilluminate "good" lamp GL and cause the control gate CG to change stateand shut the machine down to complete the buffing operation. If thebuffing operation has not been completed in 3-5 minutes, however,generator MTG will cause the control gate CG to change state to stop theoperation of the machine 10.

The set point output from buff level network BLN may by manually changedthrough mode selector switch MSS and mode latch ML at any time duringmachine operation. For instance, manipulation of switch MSS to causelatch ML to generate an "over buff" output will select a higher setpoint output from buff level network BLN to comparator BC and illuminate"over buff" lamp OBL. On the other hand, manipulation of switch MSS tocause latch ML to generate a "fine buff" output will select a lower setpoint output from buff level network BLN to comparator BC and illuminate"fine buff" lamp FBL. The machine 10 will operate in either of thesemodes similarly to the normal mode described above except that the tireassembly TA will be buffed to the particular set point level.

The permissible loaded radial runout range in the tire assembly TA isdetermined by the particular construction of the tire T and/or thevehicle suspension system with which the tire assembly TA is to be used.While the permissible range may vary, a permissible loaded radial runoutrange less than 0.02 inch is normally acceptable. The reject limit inthe loaded radial runout of tire assembly TA is established by thepermissible amount of tread that may remain after correction to permit areasonable tread life and is usually about 0.08 inch of loaded radialrunout. Thus, the fixed reject limit FRL is set at about 0.080 inchloaded radial runout, the normal set point in network BLN is about 0.020inch loaded radial runout, the "over buff" set point in network BLN isabout 0.050 inch loaded radial runout, and the "fine buff" set point innetwork BLN is about 0.016 inch loaded radial runout. The particularselected set point in buff level network BLN used during the stabilizingand determination periods are lowered about 0.004 inch during thecorrection period to assure reliability of correction.

what is claimed as invention is:
 1. A tire balancing machine forbalancing a tire assembly having an inflated pneumatic tire mounted on avehicular wheel rim with an effective axis of rotation comprising:abalancer drive spindle rotatable about a balancer spindle axis; balancerdrive key means fixedly mounted on and rotatable with said balancerdrive spindle; a tire assembly mounting adapter removably mounting thetire assembly thereon independently of said balancer drive spindle andhaving an adapter central axis for fixedly yet removably mounting thetire assembly thereon so that the effective axis of rotation of the tireassembly coincides with the adapter central axis, said adapter includingdrive means for engaging the tire assembly while the tire assembly ismounted on said adapter for maintaining a fixed rotational position ofthe tire assembly relative to said adapter, said adapter defining aspindle receiving passage therethrough concentric about said adaptercentral axis so that said balancer drive spindle is slidably receivabletherethrough to removably mount said adapter with the tire assemblythereon on said balancing machine with the adapter central axiscoinciding with said balancer spindle axis, and said adapter includingkey engaging means for engaging said balancer drive key means when saidadapter is mounted on said balancer drive spindle; and adapter lockingmeans for selectively engaging said balancer drive spindle and said tiremounting adapter to force said key engaging means on said tire mountingadapter into engagement with said balancer drive key means, saidbalancer drive key means and said key engaging means constructed andarranged so that engagement between said balancer drive key means andsaid key engaging means maintains said tire mounting adapter fixedaxially along the length of said balancer drive spindle and fixedrotationally with respect to said balancer drive spindle.
 2. A tirebalancing machine for balancing a tire assembly having an inflatedpneumatic tire mounted on a vehicular wheel rim with an effectiverotational axis comprising:a balancer drive spindle rotatable about abalancer spindle axis; balancer drive key means including a balancerdrive key member fixedly mounted on and rotatable with said balancerdrive spindle; and a tire assembly mounting adapter having an adaptercentral axis for fixedly yet removably mounting the tire assemblythereon so that the effective axis of rotation of the tire assemblycoincides with the adapter central axis, said adapter including drivemeans for engaging the tire assembly while the tire assembly is mountedon said adapter for maintaining a fixed rotational position of the tireassembly relative to said adapter, said adapter defining a spindlereceiving passage therethrough concentric about said adapter centralaxis so that said balancer drive spindle is slidably receivabletherethrough to removably mount said adapter with the tire assemblythereon on said balancing machine with the adapter central axiscoinciding with said balancer spindle axis, and said adapter includingkey engaging means for engaging said balancer drive key means when saidadapter is mounted on said balancer drive spindle for maintaining afixed rotational position between said adapter and said balancer drivespindle, said key engaging means including a key engaging slot having asubstantially constant width along its length defined in said adapterand opening into said spindle receiving passage; said drive key memberbeing tapered so that said drive key member will slidably fit into saidkey engaging slot to positively locate said tire assembly mountingadapter on said balancer drive spindle.
 3. The tire balancing machine ofclaim 2 further including adapter locking means for selectively lockingsaid tire assembly mounting adapter on said balancer drive spindle whilesaid key engaging means is engaging said balancer drive key means formaintaining a fixed rotational position between said adapter and saidbalancer drive spindle.
 4. The tire balancing machine of claim 2 whereinsaid tire assembly mounting adapter includes a support member definingsaid spindle receiving passage therethrough and said key engaging slottherein; a wheel positioning assembly adapted to be removably mounted onsaid support member; and a positioning locking member for selectivelyengaging said support member to fixedly yet removably mount said wheelpositioning assembly on said support member, said support member furtherincluding abutment means thereon engaging said wheel positioningassembly in opposition to said positioning locking member to limit themovement of said wheel positioning assembly axially of said supportmember so that said wheel positioning assembly is fixedly yet removablymounted on said support member between said abutment means and saidpositioning locking member, and interconnecting means engaging saidwheel positioning assembly mounted on said support member to maintainsaid wheel positioning assembly rotationally fixed with respect to saidsupport member, said wheel position in assembly constructed and arrangedto locate said tire assembly with respect to said support member so thatthe effective rotational axis of said tire assembly coincides with theadapter central axis of said upper support member and to clamp thevehicular wheel rim therein so that the tire assembly is rotationallyfixed with respect to said wheel positioning assembly while said wheelpositioning assembly is fixedly mounted on said support member betweensaid abutment means and said positioning locking member.
 5. The tirebalancing machine of claim 4 adapted to locate the tire assembly usingthe central opening through the central disk on the vehicular wheel rimwhere the central opening is concentric with the effective rotationalaxis of the tire assembly wherein said wheel positioning assemblyincludes a backup member adapted to be removably mounted on said supportmember; a clamping member adapted to be removably mounted on saidsupport member; a locating cone adapted to be removably mounted on saidsupport member between said backup member and said clamping member; andspring means adapted to be removably mounted on said support memberbetween said backup member and said clamping member, said backup memberand said clamping member constructed and arranged to be forced towardeach other by said abutment means and said positioning locking member toclamp the central disk of the wheel rim therebetween, and said locatingcone and said spring means constructed and arranged so that saidlocating cone engages the central opening through the central disk onthe vehicular wheel rim positioned between said backup member and saidclamping member and locates the central opening concentrically of theadapter central axis whereby the effective rotational axis of the tireassembly coincides with the adapter central axis.
 6. The tire balancingmachine of claim 4 adapted to locate the tire assembly using the lugholes through the central disk on the vehicular wheel rim which arearranged concentrically of the effective rotational axis of the tireassembly wherein said wheel positioning assembly includes a pair ofadapter plates adapted to be removably mounted on said support memberand forced toward each other by said abutment means and said positioninglocking member, each of said adapter plates defining a plurality ofslots therethrough radially oriented with respect to the adapter centralaxis when said adapter plate is mounted on said support member, saidplurality of slots corresponding in number and circumferential spacingto the lug holes in the vehicular wheel rim; and a plurality of adapterstuds constructed and arranged to extend between said adapter plates andengage said slots in said adapter plates, said adapter studs adapted toextend through the lug holes in the vehicular wheel rim and, incombination with said adapter plates, locate the vehicular wheel rim sothat the effective axis of rotation of the tire assembly coincides withthe adapter central axis and clamp the vehicular wheel rim between saidadapter studs and one of said adapter plates while said abutment meansand said locking member force said adapter plates toward each other.